Method of fabricating array substrate, array substrate and display device

ABSTRACT

A display device is disclosed. The display device includes a display area and a wiring area. The display area is disposed with a first thin film transistor which is an oxide thin film transistor and a second thin film transistor which is a low temperature poly-silicon thin film transistor. A distance between a first active layer of the first thin film transistor and a substrate is different from a distance between a second active layer of the second thin film transistor and the substrate. The first thin film transistor includes first vias that receive a first source/drain. The second thin film transistor includes second vias that receives a second source/drain. The wiring area is provided with a groove. The groove includes a first sub-groove and a second sub-groove that are stacked, and depths of the second vias are substantially equal to a depth of the second sub-groove.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation Application of Ser. No.16/486,990, filed on Aug. 19, 2019 and entitled “METHOD OF FABRICATINGARRAY SUBSTRATE, ARRAY SUBSTRATE AND DISPLAY DEVICE”, which itself is a35 U.S.C. 371 national stage application of PCT InternationalApplication No. PCT/CN2018/120250, filed on Dec. 11, 2018, which claimsthe benefit of Chinese Patent Application No. 201810215915.2, filed onMar. 15, 2018, the entire disclosures of which are incorporated hereinby reference.

TECHNICAL FIELD

The present disclosure relates to the field of display technologies, andin particular, to a method of fabricating an array substrate, an arraysubstrate and a display device.

BACKGROUND

Both low temperature poly-silicon (LTPS) thin film transistors and oxidethin film transistors can be used in display devices, and arraysubstrates in which oxide thin film transistors and low temperaturepoly-silicon thin film transistors are combined have currently appeared.However, the fabrication processes of these two kind of thin filmtransistors are incompatible and may result in problems such as poorprocess stability, long production cycle, complicated process and highprocess cost.

SUMMARY

According to an aspect of the present disclosure, a display device isprovided. The display device comprises a display area and a wiring area.The display area is provided with a first thin film transistor and asecond thin film transistor, the first thin film transistor comprises anoxide thin film transistor, and the second thin film transistorcomprises a low temperature poly-silicon thin film transistor. Adistance between a first active layer of the first thin film transistorand a substrate is different from a distance between a second activelayer of the second thin film transistor and the substrate. A firstsource/drain of the first thin film transistor is electrically connectedto the first active layer through first vias, a second source/drain ofthe second thin film transistor is electrically connected to the secondactive layer through second vias. The wiring area is provided with agroove, the groove comprises a first sub-groove and a second sub-groovethat are stacked, and depths of the second vias are substantially equalto a depth of the second sub-groove.

In some embodiments, depths of the first vias are substantially equal toa depth of the first sub-groove.

In some embodiments, the first source/drain fills the first vias so thata portion of the first active layer exposed by the first vias is coveredby the first source/drain.

In some embodiments, the display device further comprises a wiring, andthe wiring is in the groove and made of a same material as the secondsource/drain.

In some embodiments, the display device further comprises a firstconnection line. An electrode of the first source/drain is electricallyconnected to an electrode of the second source/drain through the firstconnection line, and the first connection line is made of a samematerial as the second source/drain.

In some embodiments, the first connection line and the secondsource/drain are formed by a same process.

In some embodiments, the display device further comprises a firstplanarization layer. The first planarization layer is on a side of thefirst source/drain and the second source/drain away from the substrate,and at least a part of the groove is filled with the first planarizationlayer, and a thickness of a portion of the first planarization layer inthe groove is thicker than a thickness of other portions of the firstplanarization layer.

In some embodiments, the display device further comprises a secondconnection line and a wiring. The second connection line is on a side ofthe first planarization layer away from the substrate, and one end ofthe second connection line is electrically connected to the otherelectrode of the second source/drain that is not electrically connectedto the first connection line through a fourth via penetrating the firstplanarization layer. The wiring is in the groove and made of a samematerial as the second connection line.

In some embodiments, the wiring and the second connection line areformed by a same process.

In some embodiments, the display device further comprises a secondplanarization layer. The second planarization layer is on a side of thesecond connection line away from the substrate, and a portion of thesecond planarization layer is filled in the groove and is on a side ofthe wiring away from the substrate.

In some embodiments, the display device further comprises an anode of anorganic light emitting diode. The anode of the organic light emittingdiode is on a side of the second planarization layer away from thesubstrate and is electrically connected to the other end of the secondconnection line through a via penetrating the second planarizationlayer.

In some embodiments, the display device further comprises a firstauxiliary electrode and a third auxiliary electrode. The first auxiliaryelectrode is on a side of the second active layer away from thesubstrate and made of a same material as the second source/drain and thefirst connection line. The third auxiliary electrode is between thesecond active layer and the first auxiliary electrode and made of a samematerial as a first gate of the first thin film transistor. The firstauxiliary electrode and the third auxiliary electrode are electricallyinsulated from each other.

In some embodiments, the first auxiliary electrode, the secondsource/drain, and the first connection line are formed by a sameprocess, and the third auxiliary electrode and the first gate of thefirst thin film transistor are formed by a same process.

In some embodiments, the first auxiliary electrode is electricallyinsulated from the second source/drain.

In some embodiments, the display device further comprises: a second gateinsulating layer on the substrate; a second gate of the second thin filmtransistor on a side of the second gate insulating layer away from thesubstrate; and a second interlayer insulating layer on a side of thesecond gate away from the substrate and covering the second gate.

According to another aspect of the present disclosure, a display deviceis provided. The display device comprises a display area and a wiringarea. The display area is provided with a first thin film transistor anda second thin film transistor, the first thin film transistor comprisesan oxide thin film transistor, and the second thin film transistorcomprises a low temperature poly-silicon thin film transistor. Adistance between a first active layer of the first thin film transistorand a substrate is different from a distance between a second activelayer of the second thin film transistor and the substrate. A firstsource/drain of the first thin film transistor is electrically connectedto the first active layer through first vias, a second source/drain ofthe second thin film transistor is electrically connected to the secondactive layer through second vias. The wiring area is provided with agroove, the groove comprises a first sub-groove and a second sub-groovethat are stacked, the first sub-groove and the first vias are formed bya same process, and the second sub-groove and the second vias are formedby a same process.

In some embodiments, depths of the first vias are substantially equal toa depth of the first sub-groove.

In some embodiments, depths of the second vias are substantially equalto a depth of the second sub-groove.

In some embodiments, the first source/drain fills the first vias so thata portion of the first active layer exposed by the first vias is coveredby the first source/drain.

In some embodiments, the display device further comprises a wiring, andthe wiring is in the groove and made of a same material as the secondsource/drain.

In some embodiments, the display device further comprises a firstconnection line. An electrode of the first source/drain is electricallyconnected to an electrode of the second source/drain through the firstconnection line, and the first connection line is made of a samematerial as the second source/drain.

In some embodiments, the first connection line and the secondsource/drain are formed by a same process.

In some embodiments, the display device further comprises a firstplanarization layer. The first planarization layer is on a side of thefirst source/drain and the second source/drain away from the substrate,and at least a part of the groove is filled with the first planarizationlayer, and a thickness of a portion of the first planarization layer inthe groove is thicker than a thickness of other portions of the firstplanarization layer.

In some embodiments, the display device further comprises a secondconnection line and a wiring. The second connection line is on a side ofthe first planarization layer away from the substrate, and one end ofthe second connection line is electrically connected to the otherelectrode of the second source/drain that is not electrically connectedto the first connection line through a fourth via penetrating the firstplanarization layer. The wiring is in the groove and made of a samematerial as the second connection line.

In some embodiments, the wiring and the second connection line areformed by a same process.

In some embodiments, the display device further comprises a secondplanarization layer. The second planarization layer is on a side of thesecond connection line away from the substrate, and a portion of thesecond planarization layer is filled in the groove and is on a side ofthe wiring away from the substrate.

In some embodiments, the display device further comprises an anode of anorganic light emitting diode. The anode of the organic light emittingdiode is on a side of the second planarization layer away from thesubstrate and is electrically connected to the other end of the secondconnection line through a via penetrating the second planarizationlayer.

In some embodiments, the display device further comprises a firstauxiliary electrode and a third auxiliary electrode. The first auxiliaryelectrode is on a side of the second active layer away from thesubstrate and made of a same material as the second source/drain and thefirst connection line. The third auxiliary electrode is between thesecond active layer and the first auxiliary electrode and made of a samematerial as a first gate of the first thin film transistor. The firstauxiliary electrode and the third auxiliary electrode are electricallyinsulated from each other.

In some embodiments, the first auxiliary electrode, the secondsource/drain, and the first connection line are formed by a sameprocess, and the third auxiliary electrode and the first gate of thefirst thin film transistor are formed by a same process.

In some embodiments, the first auxiliary electrode is electricallyinsulated from the second source/drain.

In some embodiments, the display device further comprises: a second gateinsulating layer on the substrate; a second gate of the second thin filmtransistor on a side of the second gate insulating layer away from thesubstrate; and a second interlayer insulating layer on a side of thesecond gate away from the substrate and covering the second gate.

According to yet another aspect of the present disclosure, a displaydevice is provided. The display device comprises a display area and awiring area. The display area is provided with a first thin filmtransistor and a second thin film transistor, the first thin filmtransistor comprises an oxide thin film transistor, and the second thinfilm transistor comprises a low temperature poly-silicon thin filmtransistor. A distance between a first active layer of the first thinfilm transistor and a substrate is different from a distance between asecond active layer of the second thin film transistor and thesubstrate. A first source/drain of the first thin film transistor iselectrically connected to the first active layer through first vias, asecond source/drain of the second thin film transistor is electricallyconnected to the second active layer through second vias. The wiringarea is provided with a groove, the groove comprises a first sub-grooveand a second sub-groove that are stacked. The display device furthercomprises a first connection line, and an electrode of the firstsource/drain is electrically connected to an electrode of the secondsource/drain through the first connection line.

In some embodiments, the first connection line is made of a samematerial as the second source/drain.

In some embodiments, the first connection line and the secondsource/drain are formed by a same process.

In some embodiments, depths of the first vias are substantially equal toa depth of the first sub-groove.

In some embodiments, depths of the second vias are substantially equalto a depth of the second sub-groove.

In some embodiments, the first source/drain fills the first vias so thata portion of the first active layer exposed by the first vias is coveredby the first source/drain.

In some embodiments, the display device further comprises a wiring, andthe wiring is in the groove and made of a same material as the secondsource/drain.

In some embodiments, the display device further comprises a firstplanarization layer. The first planarization layer is on a side of thefirst source/drain and the second source/drain away from the substrate,and at least a part of the groove is filled with the first planarizationlayer, and a thickness of a portion of the first planarization layer inthe groove is thicker than a thickness of other portions of the firstplanarization layer.

In some embodiments, the display device further comprises a secondconnection line and a wiring. The second connection line is on a side ofthe first planarization layer away from the substrate, and one end ofthe second connection line is electrically connected to the otherelectrode of the second source/drain that is not electrically connectedto the first connection line through a fourth via penetrating the firstplanarization layer. The wiring is in the groove and made of a samematerial as the second connection line.

In some embodiments, the wiring and the second connection line areformed by a same process.

In some embodiments, the display device further comprises a secondplanarization layer. The second planarization layer is on a side of thesecond connection line away from the substrate, and a portion of thesecond planarization layer is filled in the groove and is on a side ofthe wiring away from the substrate.

In some embodiments, the display device further comprises an anode of anorganic light emitting diode. The anode of the organic light emittingdiode is on a side of the second planarization layer away from thesubstrate and is electrically connected to the other end of the secondconnection line through a via penetrating the second planarizationlayer.

In some embodiments, the display device further comprises a firstauxiliary electrode and a third auxiliary electrode. The first auxiliaryelectrode is on a side of the second active layer away from thesubstrate and made of a same material as the second source/drain and thefirst connection line. The third auxiliary electrode is between thesecond active layer and the first auxiliary electrode and made of a samematerial as a first gate of the first thin film transistor. The firstauxiliary electrode and the third auxiliary electrode are electricallyinsulated from each other.

In some embodiments, the first auxiliary electrode, the secondsource/drain, and the first connection line are formed by a sameprocess, and the third auxiliary electrode and the first gate of thefirst thin film transistor are formed by a same process.

In some embodiments, the first auxiliary electrode is electricallyinsulated from the second source/drain.

In some embodiments, the display device further comprises: a second gateinsulating layer on the substrate; a second gate of the second thin filmtransistor on a side of the second gate insulating layer away from thesubstrate; and a second interlayer insulating layer on a side of thesecond gate away from the substrate and covering the second gate.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or additional aspects and advantages of the presentdisclosure will become apparent and readily understood from thedescription of embodiments with reference to the following drawings, inwhich:

FIG. 1 schematically shows a related array substrate comprising twokinds of thin film transistors;

FIG. 2 schematically shows a flow chart of a method of fabricating anarray substrate in accordance with an embodiment of the presentdisclosure;

FIG. 3 schematically shows a flow chart of a method of fabricating anarray substrate in accordance with another embodiment of the presentdisclosure;

FIG. 4A-4E schematically show structures of an array substrate incertain stages of the method of FIG. 3;

FIG. 5 schematically shows a flow chart of a method of fabricating anarray substrate in accordance with yet another embodiment of the presentdisclosure;

FIG. 6A-6B schematically show the structures of an array substrate incertain stages of the method of FIG. 5;

FIG. 7 schematically shows an array substrate in accordance with anembodiment of the present disclosure; and

FIG. 8 schematically shows an array substrate in accordance with anotherembodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

With the development of semiconductor manufacturing technology anddisplay technology, users' requirements for the performance of displaydevices have also increased. For example, display devices with highdefinition, high contrast, and high aperture ratio are increasinglypopular with users. In addition, new display devices using technologiessuch as flexible screens, narrow or free of bezels have also shown greatmarket prospects. Array substrates, such as back plates of organic lightemitting display devices, are important components that affect theperformance of the display devices. Thin film transistors are importantswitching control components in array substrates. In recent years, lowtemperature poly-silicon thin film transistors and oxide thin filmtransistors have attracted much attention in the display industry. Thelow temperature poly-silicon thin film transistor, the active layer ofwhich is made of a poly-silicon material, has advantages of high carriermobility and fast charging. The oxide thin film transistor, the activelayer of which is made of an oxide material such as IGZO, has anadvantage of small leakage current. Therefore, an array substrate inwhich an oxide thin film transistor and a low temperature poly-siliconthin film transistor are combined has appeared.

However, currently, the array substrate comprising multiple kinds ofthin film transistors (such as low temperature poly-silicon thin filmtransistors and oxide thin film transistors) and the manufacturingmethod thereof, generally have problems such as poor manufacturingstability, long manufacturing period, complicated process and high cost.This is mainly because the poor compatibility of the fabricationprocesses of the low-temperature poly-silicon thin film transistor andthe oxide thin film transistor.

FIG. 1 schematically shows a related array substrate comprising twokinds of thin film transistors. These two kinds of thin film transistorsmay be a low temperature poly-silicon thin film transistor and an oxidethin film transistor. In this array substrate, the source/drains of thetwo kinds of transistors (i.e., the first source/drain 440 of the oxidethin film transistor and the second source/drain 340 of the lowtemperature poly-silicon thin film transistor) are disposed in the samelayer. The term “disposed in the same layer” does not mean that theentireties of the structures are disposed in the one and only layer;instead, it may means that a portion of a first structure and a portionof a second structure are co-existent in the same layer. The firstsource/drain 440 of the oxide thin film transistor is connected to anactive layer (i.e., the first active layer 420) of the oxide thin filmtransistor through first vias. The second source/drain 340 of the lowtemperature poly-silicon thin film transistor is connected to an activelayer (i.e., the second active layer 310) of the low temperaturepoly-silicon thin film transistor through second vias. The thickness ofthe insulating layers above the low temperature poly-silicon thin filmtransistor (comprising a second interlayer insulating layer 350, a firstbuffer layer 410 and a first interlayer insulating layer 460) is largerthan the thickness of the insulating layer above the oxide thin filmtransistor (comprising the first interlayer insulating layer 460) due tothe difference in materials of the active layers. Therefore, if the twokinds of thin film transistors are formed in the one and same etchingprocess, the moment the vias of the oxide thin film transistor reach theoxide semiconductor active layer, the vias of the low temperaturepoly-silicon thin film transistor has not yet reached the poly-siliconactive layer. In the continuing process of forming the vias of the lowtemperature poly-silicon thin film transistor, the active layer of theoxide thin film transistor is easily affected, such that the switchingcharacteristics of the oxide thin film transistor may be harmed. Inaddition, before the active layer of the low temperature poly-siliconthin film transistor is in contact with the source/drain, it is neededto clean the surfaces of the low temperature poly-silicon active layerwhich is exposed through the vias with hydrofluoric acid to remove thesurface oxide layers, such that a good ohm contact can be formed betweenthe low temperature poly-silicon active layer and the subsequentlyformed source/drain of the low temperature poly-silicon film transistor.However, the cleaning process may affect the oxide semiconductor activelayer, thereby affecting the switching characteristics of the oxide thinfilm transistor. For the above reasons, the fabrication processes of thelow temperature poly-silicon thin film transistor and the oxide thinfilm transistor are not compatible. Therefore, it is necessary to designa fabrication method that can solve the incompatibility of the lowtemperature poly-silicon thin film transistor and the oxide thin filmtransistor. In addition, since display devices are expected to havenarrow or free of bezels, as well as flexible display functions, it isdesirable that such a fabrication method can simultaneously meet otherrequirements.

Embodiments of the present disclosure are described in detail below withreference to the accompanying drawings. The same or similar referencenumerals indicate the same or similar elements or elements having thesame or similar functions throughout the disclosure. The embodimentsdescribed below with reference to the drawings are exemplary. Theyintend to explain the present disclosure only, and should not beunderstood as a limitation of the present disclosure.

In one aspect of the disclosure, a method of fabricating an arraysubstrate is provided. The array substrate may comprise multiple kindsof thin film transistors. Specifically, depths of the active layers ofdifferent kinds of thin film transistors may be inconsistent. The term“depth” may mean the distance from the substrate to the active layer ina direction perpendicular to the substrate. The array substratecomprises a display area 111 and a wiring area 112. The wiring area 112has a groove. The first thin film transistor 400 is connected in serieswith the second thin film transistor 300. The first thin film transistor400 and the second thin film transistor 300 may be located in thedisplay area 111 and may also be located in the wiring area 112. Thearray substrate may be a back plate of an organic light emitting displaydevice. For example, the array substrate may be a back plate of a screenhaving narrow bezel even no bezel or a flexible screen of an organiclight emitting display device. The substrate 100 of the array substratemay be a flexible substrate, e.g. a substrate formed of polyimide (PI).

In an embodiment of the present disclosure, the array substrate maycomprise both oxide thin film transistors and low temperaturepoly-silicon thin film transistors. In some embodiments, the first thinfilm transistor 400 may be the oxide thin film transistor, and thesecond thin film transistor 300 may be the low temperature poly-siliconthin film transistor. It should be noted that the above-describedspecific types of the first thin film transistor and second thin filmtransistor are merely examples. Other types of transistors are equallyapplicable to the present disclosure. The specific types are notparticularly limited in the present disclosure.

FIG. 2 schematically shows a method of fabricating an array substrate inaccordance with an embodiment of the present disclosure. The methodcomprises:

S100: simultaneously forming first vias and a first sub-groove, and

S200: simultaneously forming second vias and a second sub-groove.

The term “simultaneously forming” means that two or more structures areformed in the same process step, which means the two or more structuresare formed a single exposure process using a single mask. In contrast tothe method of simultaneously forming the first vias and the second vias,in the method according to an embodiment of the present disclosure, thefirst vias and the second vias are independently formed. This method cansolve the above-described problem of incompatibility. Specifically, thismethod can avoid the problem of over-etching of the active layer of oneof the thin film transistors due to the difference in the depths of thevias of the two kinds of thin film transistors. In addition, since thetwo kinds of vias are formed in two steps, before cleaning the activelayer at a deeper position (i.e., closer to the substrate 100), theactive layer at a shallower position can be protected in advance toprevent corrosion.

In addition, in view of the current display device, particularly theorganic light-emitting flexible display device, in order to improve thebendability of the display panel, needs to etch away multilayerinorganic structures (e.g., the interlayer insulating layer, thepassivation layer, etc.) in the wiring area 112 to remove the brittleinorganic layers that are prone to crack during bending, and, for thepurpose of ensuring etching precision and product yield, the process ofremoving inorganic structures generally comprises two steps (i.e.,forming a first sub-groove and forming a second sub-groove, with thefirst sub-groove and the second sub-groove being stacked, and the firstsub-groove being further away from the substrate than the secondsub-groove), the process of removing the inorganic structures may becombined with the processes of forming the first vias and the secondvias. For example, form the first sub-groove while forming the firstvias, and form the second sub-groove while forming the second vias. Inthis way, the incompatible manufacturing processes of the two thin filmtransistors can be solved and the etching precision of the wiring areacan be guaranteed without significantly increasing the complexity of theproduction process.

A method of fabricating an array substrate in accordance with anembodiment of the present disclosure is described in more detail below.

FIG. 3 schematically shows a flow chart of a method of fabricating anarray substrate in accordance with another embodiment of the presentdisclosure. The method can comprise the following steps:

S100: simultaneously forming first vias and a first sub-groove;

S10: forming a first source/drain;

S20: forming a passivation layer;

S200: simultaneously forming second vias and a second sub-groove;

S30: cleaning the sections of the second active layer at the secondvias; and

S300: forming a second source/drain and a first connection line.

FIG. 4A-4E schematically show the structures of an array substrate incertain stages of the method of FIG. 3. FIG. 4A shows the structure ofthe array substrate after the realization of step S100. The distance L1between the first active layer 420 of the first thin film transistor andthe substrate 100 is different from the distance L2 between the secondactive layer 310 of the second thin film transistor and the substrate100. In step S100, the first vias 20 and the first sub-groove 11 may beformed in the one and same patterning process. More specifically, afterforming the first interlayer insulating layer 460, the first vias 20 andthe first sub-groove 11 can be formed in the one and same process byphotoresist coating, exposure by means of a mask, development, etching,and stripping. The specific parameters of the patterning process are notparticularly limited. The patterning process can be either dry etchingor wet etching.

Since the first sub-groove 11 and the first vias 20 are formed in thesame process, the depth of the first sub-groove 11 and the depths of thefirst vias 20 may both be H as shown in FIG. 4A. The depth of theetching can be controlled to prevent damage to the sections of firstactive layer 420 at the first vias 20 due to the depth of the first vias20 being too deep.

The (base) substrate 100 of the array substrate can be formed by aflexible material. In this case, the flexible substrate may be placed ona glass substrate 110 to perform the fabrication process. The arraysubstrate may further comprise structures such as a second buffer layer200, a second gate insulating layer 320, a second gate 330, a secondinterlayer insulating layer 350, a first buffer layer 410, and a firstgate 430. The specific positions and materials of the above-describedstructures are not particularly limited. Those skilled in the art canmake a selection according to actual conditions. For example, the secondbuffer layer 200 may be a single-layer structure or a multilayerstructure. The remaining layers, such as the interlayer insulatinglayers, the gate insulating layers, the gates, etc., may be selectedaccording to the materials of the active layer and specific requirementsfor the array substrate of different products.

In some embodiments, after forming the first vias 20 and the firstsub-groove 11, the first source/drain 440 may be formed (step S10). Thefirst source/drain 440 is electrically connected to the first activelayer 420 through the first vias 20. It should be understood that theterm “source/drain” refers to a collection of a source and a drain, andone electrode of the source/drain is the source and the other one is thedrain. FIG. 4B schematically shows the structure of the array substrateafter the step S10, that is, after the first source/drain 440 has beenformed. The first source/drain 440 can be formed by conventionaldeposition and patterning processes. The formed first source/drain 440fills the first vias 20, and the sections of first active layer 420 atthe first via 20 are covered by the first source/drain 440, so the firstsource/drain 440 can protect the sections of the first active layer 420at the first vias 20.

After forming the first source/drain 440, the passivation layer 500 maybe formed. FIG. 4C schematically shows the structure of the arraysubstrate after the step S30, that is, after forming the passivationlayer 500. The material of the passivation layer 500 is not particularlylimited, as long as the thin film transistor can be protected. Thoseskilled in the art can select a suitable material to form thepassivation layer 500.

After forming the passivation layer 500, the second sub-groove 12 andthe second vias 30 may be simultaneously formed (step S200). The secondvias are formed by etching the passivation layer 500, the firstinterlayer insulating layer 460, the first buffer layer 410, the secondinterlayer insulating layer 350 and the second gate insulating layer320. The depth of the second sub-groove 12 is not limited. FIG. 4Dschematically shows the array substrate after the step S200, that is,after forming the second sub-groove 12 and the second vias 30. Since thesecond vias 30 of the second thin film transistor is not formedsimultaneously together with the first vias 20 of the first thin filmtransistor, the problem of over-etching of the shallower active layer(i.e., the first active layer 420) when simultaneously forming the twokinds of vias due to the difference in the depths of the two kinds ofvias can be avoided. Moreover, since the above-described two kinds ofvias are respectively formed simultaneously with other structures, theproduction process is not prolonged.

In some embodiments, the second vias 30 and the second sub-groove 12 maybe formed by a patterning process similar to the formation of the firstvias 20 and the first sub-groove 11, e.g. by dry etching or wet etching.By forming the first sub-groove 11 and the second sub-groove 12, aportion of the inorganic layer structure at the wiring area 112 can beremoved to improve the mechanical performance of the array substrate. Inaddition, since the groove is formed by two steps, it is possible toavoid the difficulty in controlling the etching precision caused by theone-step process of forming the grooves, which may affect the productyield. The specific shapes and positions of the first sub-groove 11 andthe second sub-groove 12 are not particularly limited, as long as theabove-described effects can be achieved. For example, in someembodiments, the width of the first sub-groove 11 and the width of thesecond sub-groove 12 may be equal, that is, the combination of the firstsub-groove 11 and the second sub-groove 12 may constitute a groove withequal width at different depths. Alternatively, the gradients of thewidths of the first sub-groove 11 and the second sub-groove 12 may bethe same, that is, the side surface of the first sub-groove 11 and theside surface of the second sub-groove 12 form a continuous surface. Inother embodiments, the widths of the first sub-groove 11 and the secondsub-groove 12 may not be particularly limited. For example, thecombination of the first sub-groove 11 and the second sub-groove 12 mayconstitute a groove with a step-like structure. Specifically, the widthat each depth in the second sub-groove 12 is smaller than the width ateach depth in the first sub-groove 11. In this case, the secondsub-groove can be formed by etching a portion of the bottom of the firstsub-groove. In some embodiments, the second sub-groove 12 may be formedby etching only a portion of the bottom of the first sub-groove 11 bydry etching. This can prevent the possible influences on the sidesurface of the first sub-groove 11 during the etching of the secondsub-groove 12. In addition, the specific depth of the second sub-groove12, that is, the distance between the bottom surface of the groove andthe substrate 100 is not particularly limited. Those skilled in the artcan make adjustments according to actual conditions, as long as thesubstrate 100 is not penetrated. For example, in some embodiments, thesecond sub-groove 12 may extend to a surface of the substrate 100 facingtoward the second active layer 310. In other embodiments, there may be a(part of the) buffer layer 200 (which may be composed of an inorganicmaterial) and/or other structures between the bottom of the secondsub-groove 12 and the substrate 100. Thus, the mechanical performancesof the wiring area 112 can be improved by using the flexibility of thesubstrate 100, and the inorganic structures of the wiring area 112 canbe prevented from being broken or cracked during, for example, bending.

Since the passivation layer 500 covers the first source/drain 440 thathas been formed, a third via 44 penetrating the passivation layer 500and extending to the first source/drain 440 can be formed using the samepatterning process while forming the second sub-groove 12 and the secondvias 30.

After forming the second vias 30, the sections of the second activelayer 310 at the second vias 30 may be cleaned (step S30). Since thesections of the first active layer 420 at the first vias 20 are coveredby the first source/drain 440, the oxide on the surface of the secondactive layer 310 can be removed without affecting the performance of thefirst thin film transistor. Specifically, after forming the second vias30, the exposed sections of the second active layer 310 may be cleanedusing hydrofluoric acid or the like without worrying that thehydrofluoric acid may adversely affect the first active layer 420.

After forming the second vias 30, the second source/drain 240 and thefirst connection line 50 may be formed. The second source/drain 240 iselectrically connected to the second active layer 310 through the secondvias 30. FIG. 4E schematically shows the array substrate after the stepS300, that is, after the second source/drain 240 and the firstconnection line 50 have been formed. Specifically, first, a metal layermay be deposited on the passivation layer 500 on which the secondsub-groove 12, the second vias 30 and the third via 44 have been formed.Subsequently, the second source/drain 340 and the first connection line50 are formed by a patterning process. The first connection line 50connects one electrode of the second source/drain 340 and one electrodeof the first source/drain 440. Specifically, one end of the firstconnection line 50 is connected to one electrode of the firstsource/drain 440 through the third via 44, and the other end isconnected to one electrode of the second source/drain 340. In fact, theportion of the first connection line 50 above the passivation layer 500and the portions of the second source/drain 340 over the passivationlayer 500 are located in the same layer and are formed of the samematerial. In FIG. 4E, the first connection line 50 is disposed only onone electrode of the first source/drains 440, but it should beunderstood that the display panel may comprise another first connectionline that is disposed on the other electrode of the first source/drains440. In some embodiments, while forming the second source/drain 340 andthe first connection line 50, the wiring 40 in the grooves may also beformed simultaneously. The wiring 40 can be used, for example, as aperipheral lead of the back plate to deliver a signal or electricalpotential. In some embodiments, the wiring 40 can be used as a scanline, a data line, and the like. The material of the wiring 40 is thesame as the second source/drain 340 and the first connection line 50,and a portion of the wiring 40 is on a side of the passivation layer 500away from the substrate 100, and is on the same layer as the secondsource/drain 340 and the first connection line 50. A portion of thewiring 40 may cover the passivation layer 500 outside of the grooveand/or in the groove. This method can further save production processesand improve production efficiency.

Thereafter, a planarization layer may be formed on the passivation layer500 on which the second source/drain 340, the first connection line 50and the wiring 40 have been formed, and a hole is formed in theplanarization layer, and an anode of the electroluminescent device isformed. These steps or similar steps will be detailed in otherembodiments herein.

It should be noted that the above-described first source/drain 440 andthe second source/drain 340 should be understood in a broad sense. Itwill be understood by those skilled in the art that a thin filmtransistor is a switching device with three electrodes, comprising onecontrol electrode (i.e., a gate), one source electrode, and one drainelectrode. Which electrode of the source/drains is the source electrode(or which electrode of the source/drains is the drain electrode) andwhat is the direction of the current flowing through the source/drainare determined by the type of carrier (electron or hole) in the thinfilm transistor. Therefore, the directions of the currents flowingthrough the source/drains of the thin film transistors composed ofdifferent types of active layer materials are different. The firstsource/drain comprises the source electrode and the drain electrode ofthe first thin film transistor. The second source/drain comprises thesource electrode and the drain electrode of the second thin filmtransistor. In the example that the first thin film transistor is anoxide thin film transistor and the second thin film transistor is a lowtemperature poly-silicon thin film transistor, the two kinds of thinfilm transistors are connected in series. The voltage signals in thesignal line can be input into one electrode of the source/drain of onethin film transistor and output from the other electrode of thesource/drains of the thin film transistor, and then delivered to thesource electrode or the drain electrode of the other thin filmtransistor.

FIG. 5 schematically shows a flow chart of a method of fabricating anarray substrate in accordance with yet another embodiment of the presentdisclosure. FIG. 6A-6B schematically show the structures of an arraysubstrate in certain stages of the method of FIG. 5. This embodimentalso comprises simultaneously forming the first vias and the firstsub-groove (step S100) and forming the first source/drain (step S10).The structure of the array substrate after these two steps is identicalto the structure shown in FIG. 4B. After forming the first source/drain440, the passivation layer 500 may not be deposited temporarily;instead, the second vias 30 and the second sub-groove 12 may besimultaneously formed (step S200) firstly. Then, after cleaning thesections of the second active layer 310 at the second vias 30 (stepS30), the second source/drain 340 and the first connection line 50 areformed. FIG. 6A schematically shows the array substrate after the secondsource/drain 340 and the first connection line 50 have been formed. Thefirst connection line 50 connects the one electrode of firstsource/drain 440 and one electrode of the second source/drain 340. Insome embodiments, the first connection line 50 and the secondsource/drain 340 are in the same layer and are of the same material. Thefirst connection line 50 may cover one or both of two electrodes of thefirst source/drains 440.

Subsequently, the passivation layer 500 may be formed (step S20). Theformation manner and material of the passivation layer 500 are notparticularly limited. The formation process and materials of thepassivation layer mentioned in the above embodiments of the presentdisclosure may be adopted, and the processes and materials familiar tothose skilled in the art may also be selected according to actual needsto form the passivation layer 500, as long as the thin film transistorcan be protected. The passivation layer 500 covers the first connectionline 50 and the second source/drain 340. In some embodiments, thepassivation layer 500 can cover only the display area 111. That is, thepassivation layer 500 does not cover the groove of the wiring area 112.

After forming the passivation layer 500, the method may further comprisethe following steps:

S400: forming a first planarization layer;

S500: forming second connection lines and a wiring; and

S600: forming a second planarization layer.

First, a first planarization layer 600 is formed. The firstplanarization layer 600 may be disposed at a side of the thin filmtransistor away from the substrate 100. Specifically, the firstplanarization layer may cover the previously formed passivation layer500 and fill the groove. The material and fabrication process of thefirst planarization layer 600 are not particularly limited, and can beselected by those skilled in the art according to actual conditions. Insome embodiments, the first planarization layer 600 can be composed of atransparent organic material. Thus, the first planarization layer 600can be used to provide a flat surface for the subsequent process, andthe mechanical performances of the finally formed array substrate can beenhanced and the flexibility of the wiring area can be improved sincethe first planarization layer 600 is filled into the interior of thegroove. The first planarization layer 600 may have a uniform thickness.In other embodiments, the thickness of the first planarization layer 600filled at the groove may be slightly thicker than the thickness of thefirst planarization layer 600 at other regions. Thus, the mechanicalperformances of the array substrate at the groove can be furtherimproved. In some embodiments, the thickness of the first planarizationlayer 600 at the groove may be equal to the depth of the groove or maybe slightly less than the depth of the groove. That is to say, afterforming the first planarization layer 600, the groove may be filled upby the first planarization layer 600 or may not be filled up by thefirst planarization layer 600.

After forming the first planarization layer 600, the second connectionlines 60 and the wiring 40 may be formed (step S500). Specifically,fourth vias 70 penetrating through the passivation layer 500 and thefirst planarization layer 600 may be formed firstly. The secondconnection lines 60 are connected to the second source/drain 340 throughthe fourth vias 70. In some embodiments, the second connection lines 60connected to the second source/drain 340 and the wiring 40 in the groovecan be simultaneously formed by depositing a metal layer and onepatterning process. Thus, the fabrication process can be simplified,that is, the times of patterning processes may be reduced by one. Thestructure connecting the ends of the second connection lines 60 that arenot connected to the second source/drain 340 is not particularlylimited, as long as signal transmission can be achieved and the secondthin film transistor can function. As described above, one electrode ofthe source/drain of the second thin film transistor may be connected inseries with the first thin film transistor. In this case, the otherelectrode of the source/drains of the second thin film transistor isconnected to the second connection line 60. The end of the secondconnection line 60 that is not connected to the second source/drain 340can be connected to a signal line or a structure such as an anode of anorganic light emitting diode (OLED). In addition, a second connectionline 60 may also be formed on the electrode of the second source/drain340 connected to the first source/drain 440 to reduce the resistance. Asecond connection line 60 may also be formed on the electrode of thefirst source/drain 440 that is not connected to the second source/drain340. In some embodiments, the second sub-groove 12 may not be formedsimultaneously with the second vias 30. For example, the secondsub-groove 12 may be formed during forming the fourth vias 70. That isto say, regardless of the wiring condition of the connection between thesecond thin film transistor and the first thin film transistor, thesecond sub-groove 12 and the fourth vias 70 can be formed using the samemask. When forming the second connection lines 60, the specificconnection situation of the second connection lines 60 can be designedaccording to different wiring conditions. In some embodiments, thesecond connection lines 60 can also serve as data lines, e.g. a powerline VSS or a structure such as a gate drive circuit wiring connected toa control circuit. In some embodiments, the orthographic projection ofthe first connection line 50 on the substrate and the orthographicprojection of second connection line 60 on the substrate can at leastpartially coincide. Therefore, by using the second connection line 60that is not disposed in the same layer as the second source/drain 340and the first connection line 50, the plurality of data lines that areoriginally located in the same layer and have the same extendingdirections can be changed to overlap in a direction perpendicular to thesubstrate, thereby facilitating the reduction of the area occupied bythe wiring area and realizing narrow bezels or even full screens free ofbezels.

After forming the second connection lines 60 and the wiring 40, a secondplanarization layer 700 may be formed (step S600). The specific positionof the second planarization layer 700 is not particularly limited. Forexample, the second planarization layer 700 can be above the displayarea 111 and the wiring area 112. Thereby, the second planarizationlayer 700 can further fill the groove of the wiring area 112, to improvethe flexibility of the array substrate and save the production process.

In some embodiments, the array substrate can be a back plate of an OLED.FIG. 7 schematically shows an array substrate in accordance with anembodiment of the present disclosure. The second connection line 60 canbe used to connect to the anode 800 of the OLED. Those skilled in theart can understand that, in this case, the one electrode of the secondsource/drain 340 that is not connected to the second connection line 60can be connected to one electrode of the first source/drain 440 throughthe first connection line 50. The one electrode of the firstsource/drain 440 that is not connected to the second source/drain 340may be connected to another second connection line 60. The one electrodeof the second source/drain 340 that is connected to the firstsource/drain 440 may also be connected to a further second connectionline 60.

In some embodiments, a compensation capacitor structure with relativelystrong compensation capability can also be formed. In the arraysubstrate of the display device, particularly the back plate of theOLED, in order to improve the control capability for the thin filmtransistor, a compensation circuit is usually provided. By providing acomponent such as a compensation capacitor, the actual operating gatevoltage of the thin film transistor can be maintained, such that it canbe substantially consistent with the preset gate voltage. The componentssuch as the above-mentioned compensation capacitor are usuallyfabricated simultaneously with some other structures. For example, whenforming a certain layer of metal structures (such as electrodes, varioustypes of wirings, connection lines, etc.), an island metal is reservedat a predetermined position during the patterning process. An insulatinglayer above the metal structures (such as the interlayer insulatinglayer, the passivation layer, the planarization layer, etc.) may serveas an insulating medium for the capacitive component. When forming metalstructures above the insulating layer, another island metal structure isalso reserved at the corresponding position. The compensation capacitoris formed by connecting the island metal structures to the circuit.

FIG. 8 schematically shows an array substrate in accordance with anotherembodiment of the present disclosure. In the foregoing embodiment, thethird auxiliary electrode 1 may be simultaneously formed when formingthe first gate electrode, and the first auxiliary electrode 2 may besimultaneously formed when forming the second source/drain and the firstconnection line. Finally, while forming the wiring 40, the secondauxiliary electrode 3 is formed. The above-described three auxiliaryelectrodes are separated by insulating materials, and thus compensationcapacitors with plurality of capacitors in parallel with each other canbe easily formed, thereby increasing the pixel capacitance to greatlyimprove the control capability of the compensation circuit to the gatevoltage.

Those skilled in the art will understand that the specific quantity ofauxiliary electrodes, as well as the specific number of compensationcapacitors in parallel, may be greater than that shown in FIG.8.Similarly, in other embodiments of the present application, auxiliaryelectrodes may also be simultaneously formed at similar positions usingthe patterning processes of forming a metal conductive structure such asa gate, a pixel electrode, a common electrode, or the like.

It should be noted that modifications, substitutions and variations tothe embodiments described above are possible within the scope of thepresent disclosure. For example, the planarization layer may or may notbe filled in the groove. The wiring in the groove may be formedsimultaneously with the first connection line or may be formedsimultaneously with other wiring structures (e.g., the second connectionlines). Those skilled in the art will understand that in the arraysubstrate having only one kind of thin film transistor (such as a lowtemperature poly-silicon thin film transistor), the above-describedmethod can also be used to make the fabrication process simpler. Afterforming the groove in the wiring area, the flexible material may not befilled. While forming the source/drain of the thin film transistor, adata line connected to the source/drain can be simultaneously formed.Filling the groove with the planarization layer can function as aninsulator and enhance the mechanical performances of the wiring area. Onthe side of the planarization layer away from the substrate, anotherdata line may be formed that has a same extending direction with thedata line and the orthographic projection of which on the substratecoincides with the orthographic projection of the data line on thesubstrate. The data lines above the planarization layer can be connectedto the source/drain through vias. Therefore, two data lines which areoriginally disposed in the same layer and in parallel (such as the powerline VSS and the gate drive circuit GOA wiring connected to the controlcircuit) can be changed to overlap in the vertical direction, which cannarrow the bezels of products. The above-described structure may bereferred to as a dual source/drain technique. The data line that islocated in the same layer as the second source/drain and is of the samematerial as the second source/drain is the first data line SD1, and thedata line located in the layer above the second source/drain is thesecond data line SD2. Since insulation is required between the two metalwirings, a structure similar to the first planarization layer can beused as the insulating medium, and at the same time the insulatingmedium can fill the groove to improve the mechanical performances of thewiring area.

According to another aspect of the present disclosure, an arraysubstrate is provided. The array substrate can be fabricated by theabove-described method. Therefore, the array substrate has all thefeatures and advantages of the array substrate obtained by theabove-described method, which will not be described herein again. Thearray substrate may have a structure of an array substrate fabricated bythe above-described method. Specifically, the array substrate comprisesa display area and a wiring area. A groove is comprised in the wiringarea. The array substrate further comprises a first thin film transistorand a second thin film transistor. In some embodiments, the first thinfilm transistor may be an oxide thin film transistor, and the secondthin film transistor may be a low temperature poly-silicon thin filmtransistor. A distance between a first active layer of the first thinfilm transistor and a substrate is different from a distance between asecond active layer of the second thin film transistor and thesubstrate. A first source/drain of the first thin film transistor iselectrically connected to the first active layer through first vias, anda second source/drain of the second thin film transistor is electricallyconnected to the second active layer through second vias. One of thesource/drain of the low temperature poly-silicon thin film transistorand one of the source/drain of the oxide thin film transistor areconnected by a first connection line. The groove may comprise a firstsub-groove and a second sub-groove that are stacked. The structures ofthe first sub-groove and the second sub-groove may be similar to thoseof the first sub-groove and the second sub-groove of the array substratefabricated by the above-described method. Specifically, the secondsub-groove is closer to the substrate than the first sub-groove. Depthsof the first vias are substantially equal to the depth of the firstsub-groove. Due to the influence of the factors such as the morphologyof the first active layer and the semiconductor fabrication process,there may be some difference between the depths of the first vias andthe depth of the first sub-groove. When the difference is within acertain range, it can still be considered that the depth of the firstvia is substantially equal to the depth of the first sub-groove, and iswithin the scope of the disclosure of the present application. In someembodiments, the difference can range from 0-1000 angstroms. The arraysubstrate can combine the advantages of a low-temperature poly-siliconthin film transistor and an oxide thin film transistor, and has a simplefabrication process as well as relatively high product yield.

In some embodiments, the substrate can be a flexible substrate. A bufferlayer is disposed between the substrate and the second active layer. Thesecond sub-groove can penetrate the buffer layer and extend to a surfaceof the substrate facing towards the second active layer.

The array substrate may also comprise a passivation layer. Thepassivation layer may be disposed on a side of the thin film transistoraway from the substrate. In some embodiments, the second source/drain isdisposed on a side of the passivation layer away from the substrate andis connected to the second active layer penetrating through thepassivation layer. In other embodiments, the second source/drain may bedisposed on a side of the passivation layer adjacent to the substrateand connected to the second connection lines penetrating through thepassivation layer. The wiring can be disposed in the groove. The secondsource/drain and the wiring may be located in the same layer andcomprise the same material. Thus, the production yield and productperformance of the array substrate can be further improved.

The array substrate may further comprise a first auxiliary electrode anda second auxiliary electrode. Specifically, the second source/drain 340,the first connection line 50 and the first auxiliary electrode 2 arelocated in the same layer and comprise the same material. The secondconnection lines 60, the wiring 40 and the second auxiliary electrode 3are located in the same layer and comprise the same material. Aninsulating layer (such as at least one of the passivation layer 500 andthe first planarization layer 600) is disposed between the firstauxiliary electrode 2 and the second auxiliary electrode 3. Theorthographic projection of the first auxiliary electrode 2 on thesubstrate 100 and the orthographic projection of the second auxiliaryelectrode 3 on the substrate 100 at least partially overlap, and theoverlapping regions are located within an orthographic projection of thesecond active layer 310 on the substrate. Thereby, the pixel capacitancecan be further improved, and the voltage compensation capability can beimproved. As described above, the array substrate may comprise threecapacitors connected in parallel to each other, thereby increasing thevoltage compensation capability. The specific situation of form thecompensation capacitor with the auxiliary electrodes has been describedin detail above and will not be described herein again.

The array substrate described above has a same structure andadvantageous effects as the array substrate fabricated using theabove-described method, and will not be described herein again.

According to a yet another aspect of the present disclosure, a displaydevice is also provided. The display device comprises the arraysubstrate in accordance with embodiments of the present disclosure.Therefore, the display device has all the features and advantages of theabove-described array substrate, and will not be described herein again.

In the description of the present disclosure, terms indicating theorientation or positional relationship, such as “on” and “under”, arebased on the orientation or positional relationship shown in thedrawings. Such terms are only used to assist in describing embodimentsof the present disclosure, and the embodiments of the present disclosureare not required to be constructed and operated in a particularorientation or positional relationship. These terms do not constitute alimitation of the present disclosure. In addition, the terms “first”,“second” and similar terms are used for naming purposes only and are notto be construed as indicating or implying features such as relativeimportance, order, or quantity. In some instances, detailed descriptionsof well-known devices and methods are omitted so as to not obscure thedescription of the devices and methods of the present disclosure. Thespecific terminologies used to describe a particular embodiment are notintended to limit the invention. Terms in the singular (such as “a”,“the”, etc.) are intended to comprise the same terms in plural as well,unless otherwise clearly indicated in the context. The term “comprising”indicates the existence of the stated feature, but does not exclude thepresence or addition of one or more other features. It will also beunderstood that the description of the sequence of method steps in thespecification is merely to illustrate of a flow. When a specific step ofa method is described as being performed after another step, thisspecific step can be performed right after the another step, and it isalso possible that one or more intermediate steps are performed beforeperforming this specific step, unless otherwise stated. Similarly, itwill be understood that when a connection between structures orcomponents is described, the connection can be established directly orthrough an intermediate structure or component, unless otherwise stated.

What is claimed is:
 1. A display device comprising: a display area; anda wiring area, wherein the display area is provided with a first thinfilm transistor and a second thin film transistor, the first thin filmtransistor comprises an oxide thin film transistor, and the second thinfilm transistor comprises a low temperature poly-silicon thin filmtransistor, wherein a distance between a first active layer of the firstthin film transistor and a substrate is different from a distancebetween a second active layer of the second thin film transistor and thesubstrate, wherein a first source/drain of the first thin filmtransistor is electrically connected to the first active layer throughfirst vias, a second source/drain of the second thin film transistor iselectrically connected to the second active layer through second vias,and wherein the wiring area is provided with a groove, the groovecomprises a first sub-groove and a second sub-groove that are stacked,and depths of the second vias are substantially equal to a depth of thesecond sub-groove.
 2. The display device of claim 1, wherein depths ofthe first vias are substantially equal to a depth of the firstsub-groove.
 3. The display device of claim 1, wherein the firstsource/drain fills the first vias so that a portion of the first activelayer exposed by the first vias is covered by the first source/drain. 4.The display device of claim 1, further comprising: a wiring, wherein thewiring is in the groove and made of a same material as the secondsource/drain.
 5. The display device of claim 1, further comprising: afirst connection line, wherein an electrode of the first source/drain iselectrically connected to an electrode of the second source/drainthrough the first connection line, and the first connection line is madeof a same material as the second source/drain.
 6. The display device ofclaim 5, wherein the first connection line and the second source/drainare formed by a same first process.
 7. The display device of claim 5,further comprising: a first planarization layer, wherein, the firstplanarization layer is on a side of the first source/drain and thesecond source/drain away from the substrate, and at least a part of thegroove is filled with the first planarization layer, and wherein athickness of a portion of the first planarization layer in the groove isthicker than a thickness of other portions of the first planarizationlayer.
 8. The display device of claim 7, further comprising: a secondconnection line on a side of the first planarization layer away from thesubstrate, wherein one end of the second connection line is electricallyconnected to another electrode of the second source/drain that is notelectrically connected to the first connection line through a fourth viapenetrating the first planarization layer, and a wiring in the grooveand made of a same material as the second connection line.
 9. Thedisplay device of claim 8, wherein the wiring and the second connectionline are formed by a same second process.
 10. The display device ofclaim 8, further comprising: a second planarization layer, wherein thesecond planarization layer is on a side of the second connection lineaway from the substrate, and a portion of the second planarization layeris filled in the groove and is on a side of the wiring away from thesubstrate.
 11. The display device of claim 10, further comprising: ananode of an organic light emitting diode, wherein the anode of theorganic light emitting diode is on a side of the second planarizationlayer away from the substrate and is electrically connected to anotherend of the second connection line through a via penetrating the secondplanarization layer.
 12. The display device of claim 5, furthercomprising: a first auxiliary electrode on a side of the second activelayer away from the substrate and made of a same material as the secondsource/drain and the first connection line; and a third auxiliaryelectrode between the second active layer and the first auxiliaryelectrode and made of a same material as a first gate of the first thinfilm transistor, wherein the first auxiliary electrode and the thirdauxiliary electrode are electrically insulated from each other.
 13. Thedisplay device of claim 12, wherein the first auxiliary electrode, thesecond source/drain, and the first connection line are formed by a samefirst process, and the third auxiliary electrode and the first gate ofthe first thin film transistor are formed by a same third process. 14.The display device of claim 12, wherein the first auxiliary electrode iselectrically insulated from the second source/drain.
 15. The displaydevice of claim 1, further comprising: a second gate insulating layer onthe substrate; a second gate of the second thin film transistor on aside of the second gate insulating layer away from the substrate; and asecond interlayer insulating layer on a side of the second gate awayfrom the substrate and covering the second gate.
 16. A display devicecomprising: a display area; and a wiring area, wherein the display areais provided with a first thin film transistor and a second thin filmtransistor, the first thin film transistor comprises an oxide thin filmtransistor, and the second thin film transistor comprises a lowtemperature poly-silicon thin film transistor, wherein a distancebetween a first active layer of the first thin film transistor and asubstrate is different from a distance between a second active layer ofthe second thin film transistor and the substrate, wherein a firstsource/drain of the first thin film transistor is electrically connectedto the first active layer through first vias, a second source/drain ofthe second thin film transistor is electrically connected to the secondactive layer through second vias, and wherein the wiring area isprovided with a groove, the groove comprises a first sub-groove and asecond sub-groove that are stacked, the first sub-groove and the firstvias are formed by a same first process, and the second sub-groove andthe second vias are formed by a same second process.
 17. The displaydevice of claim 16, wherein depths of the first vias are substantiallyequal to a depth of the first sub-groove.
 18. The display device ofclaim 16, wherein depths of the second vias are substantially equal to adepth of the second sub-groove.
 19. The display device of claim 16,wherein the first source/drain fills the first vias so that a portion ofthe first active layer exposed by the first vias is covered by the firstsource/drain.
 20. The display device of claim 16, further comprising awiring, wherein the wiring is in the groove and made of a same materialas the second source/drain.
 21. The display device of claim 16, furthercomprising a first connection line, wherein an electrode of the firstsource/drain is electrically connected to an electrode of the secondsource/drain through the first connection line, and the first connectionline is made of a same material as the second source/drain.
 22. Thedisplay device of claim 21, wherein the first connection line and thesecond source/drain are formed by a same third process.
 23. The displaydevice of claim 21, further comprising a first planarization layer,wherein, the first planarization layer is on a side of the firstsource/drain and the second source/drain away from the substrate, and atleast a part of the groove is filled with the first planarization layer,and a thickness of a portion of the first planarization layer in thegroove is thicker than a thickness of other portions of the firstplanarization layer.
 24. The display device of claim 23, furthercomprising a second connection line on a side of the first planarizationlayer away from the substrate, wherein one end of the second connectionline is electrically connected to another electrode of the secondsource/drain that is not electrically connected to the first connectionline through a fourth via penetrating the first planarization layer, anda wiring in the groove and made of a same material as the secondconnection line.
 25. The display device of claim 24, wherein the wiringand the second connection line are formed by a same fourth process. 26.The display device of claim 24, further comprising a secondplanarization layer, wherein the second planarization layer is on a sideof the second connection line away from the substrate, and a portion ofthe second planarization layer is filled in the groove and is on a sideof the wiring away from the substrate.
 27. The display device of claim26, further comprising an anode of an organic light emitting diode,wherein the anode of the organic light emitting diode is on a side ofthe second planarization layer away from the substrate and iselectrically connected to another end of the second connection linethrough a via penetrating the second planarization layer.
 28. Thedisplay device of claim 21, further comprising a first auxiliaryelectrode on a side of the second active layer away from the substrateand made of a same material as the second source/drain and the firstconnection line; and a third auxiliary electrode between the secondactive layer and the first auxiliary electrode and made of a samematerial as a first gate of the first thin film transistor, wherein thefirst auxiliary electrode and the third auxiliary electrode areelectrically insulated from each other.
 29. The display device of claim28, wherein the first auxiliary electrode, the second source/drain, andthe first connection line are formed by a same third process, and thethird auxiliary electrode and the first gate of the first thin filmtransistor are formed by a same fifth process.
 30. The display device ofclaim 28, wherein the first auxiliary electrode is electricallyinsulated from the second source/drain.
 31. The display device of claim16, further comprising a second gate insulating layer on the substrate;a second gate of the second thin film transistor on a side of the secondgate insulating layer away from the substrate; and a second interlayerinsulating layer on a side of the second gate away from the substrateand covering the second gate.
 32. A display device comprising a displayarea; and a wiring area, wherein the display area is provided with afirst thin film transistor and a second thin film transistor, the firstthin film transistor comprises an oxide thin film transistor, and thesecond thin film transistor comprises a low temperature poly-siliconthin film transistor, wherein a distance between a first active layer ofthe first thin film transistor and a substrate is different from adistance between a second active layer of the second thin filmtransistor and the substrate, wherein a first source/drain of the firstthin film transistor is electrically connected to the first active layerthrough first vias, a second source/drain of the second thin filmtransistor is electrically connected to the second active layer throughsecond vias, wherein the wiring area is provided with a groove, thegroove comprises a first sub-groove and a second sub-groove that arestacked, and wherein the display device further comprises a firstconnection line, and an electrode of the first source/drain iselectrically connected to an electrode of the second source/drainthrough the first connection line.
 33. The display device of claim 32,wherein the first connection line is made of a same material as thesecond source/drain.
 34. The display device of claim 33, wherein thefirst connection line and the second source/drain are formed by a sameprocess.
 35. The display device of claim 32, wherein depths of the firstvias are substantially equal to a depth of the first sub-groove.
 36. Thedisplay device of claim 32, wherein depths of the second vias aresubstantially equal to a depth of the second sub-groove.
 37. The displaydevice of claim 32, wherein the first source/drain fills the first viasso that a portion of the first active layer exposed by the first vias iscovered by the first source/drain.
 38. The display device of claim 32,further comprising: a wiring, wherein the wiring is in the groove andmade of a same material as the second source/drain.
 39. The displaydevice of claim 32, further comprising: a first planarization layer,wherein, the first planarization layer is on a side of the firstsource/drain and the second source/drain away from the substrate, and atleast a part of the groove is filled with the first planarization layer,and wherein a thickness of a portion of the first planarization layer inthe groove is thicker than a thickness of other portions of the firstplanarization layer.
 40. The display device of claim 39, furthercomprising: a second connection line on a side of the firstplanarization layer away from the substrate, wherein one end of thesecond connection line is electrically connected to another electrode ofthe second source/drain that is not electrically connected to the firstconnection line through a fourth via penetrating the first planarizationlayer, and a wiring in the groove and made of a same material as thesecond connection line.
 41. The display device of claim 40, wherein thewiring and the second connection line are formed by a same process. 42.The display device of claim 40, further comprising: a secondplanarization layer, wherein the second planarization layer is on a sideof the second connection line away from the substrate, and a portion ofthe second planarization layer is filled in the groove and is on a sideof the wiring away from the substrate.
 43. The display device of claim42, further comprising: an anode of an organic light emitting diode,wherein the anode of the organic light emitting diode is on a side ofthe second planarization layer away from the substrate and iselectrically connected to another end of the second connection linethrough a via penetrating the second planarization layer.
 44. Thedisplay device of claim 32, further comprising: a first auxiliaryelectrode on a side of the second active layer away from the substrateand made of a same material as the second source/drain and the firstconnection line; and a third auxiliary electrode between the secondactive layer and the first auxiliary electrode and made of a samematerial as a first gate of the first thin film transistor, wherein thefirst auxiliary electrode and the third auxiliary electrode areelectrically insulated from each other.
 45. The display device of claim44, wherein the first auxiliary electrode, the second source/drain, andthe first connection line are formed by a same first process, and thethird auxiliary electrode and the first gate of the first thin filmtransistor are formed by a same second process.
 46. The display deviceof claim 44, wherein the first auxiliary electrode is electricallyinsulated from the second source/drain.
 47. The display device of claim32, further comprising: a second gate insulating layer on the substrate;a second gate of the second thin film transistor on a side of the secondgate insulating layer away from the substrate; and a second interlayerinsulating layer on a side of the second gate away from the substrateand covering the second gate.